Process fob extracting prolamines



Patented July 25, 1944 UNITED s TAT raoonssroa ax'raao'rmo raoLAMmEs Ralph H. Manley andC assignors to ClaudeR.

yril n. misread n1., 7

Wickard, as Secretary of Agriculture of the United States of America,

and tofhis successors'in oflice V v I No Drawing. Application February 4, 1942,

v Serial No. 4Z9,577 I d'Claims. (01.260-123) 7 N J (Granted .under the actor Marcus, 1883, as

madman-1130,1928;3700.6.757)

This application is made under the act of March" 3, 1883, as-amended by-the act'of April 30, 1928,

and the invention'herein described "andclaimedrf if patented, may lie-manufactured and used byor for the Government of the United States of We have found'that prolamiries such as zein and gliadin may be'extracted from suitablevege- I table material such 'as corn gluten, rye gluten V or wheat gluten in high yields and without danger America for govermnental purposes without the payment to 'us of any royalty thereon. 1 This invention relates to a-;'new method of extracting prolamines from vegetable material and more particularly to the extraction of zein from corn gluten and gliadin from wheat gluten.

The present commercial method of obtainin prolamines from vegetable material comprises the extraction of the vegetable material with aque ous solutions of ethyl or. isopropyl alcohol for 1 to 2 /2 hours at 50 to 60 C. After clarification and concentration of the aqueous-alcohol extract, the prolamine is precipitated by dilution with 5 water, filtered, and dried to a powder. This pro-'- and useful essing, and yields a prolamine dispersion which does not' gel upon prolonged. storage; By virtue 16' cedure has several disadvantages, among which 7 are the following: 7 p 1. High solvent loss' during a long extraction periodu i I i 2..Difllcultyin recovering the alcohol from the system with water. w p

3. Dangerof gelation of'the prolamine. Gelation of the prolamine during and subsequent toextraction' is a particularly serious difli very dilute 'solution arising from dilution ofthe V w i dispersing media to be suitableioruse as constituents of our extraction culty inherent to the present extraction process. Since the rate of gelation of. zeinydispersions in aqueous 85 percent ethyl or isopropyl alcohol increases very rapidly with risein temperature, and since such dispersions may set to a gel in a few minutes at temperatures approachingthe" boiling points of'the solvents, great'care must be exercised to keep the temperature of the extraction mixture as low as possible. However,

. this has its limitations as the time required for extraction must be greatly extended as the temperature'of the extraction mixture is lowered.

The tendency of aqueous-alcoholic dispersions of the prolamines to set to a useless gel makes it necessary in the present process toprecipitate the protein from the solution as promptly as possible, and to convert to a dry solid for-storage purposes.

H In the preparation of aqueous-alcoholic dispersions of the prolamines for use as spiritvarnishes, it is desirable according to present practice to redisperse the driedprotein in the aque-' ous alcohol at the time the varnish is to be used; otherwisagelation may take place'with' con sequent loss of protein and-solvent.

of gelation v w 7 'material with a. prolamine dispersing medium,

by heating, the prolamine containing such as an alcohol or other suitableorganic compounds in" the presenceoi analdehyde'.

We have found that extraction of 'prolamine s by the use of prolamine dispersing media in the presence of s an aldehyde eliminates all danger of gelation during extraction and subsequent procofthis stability the prolamine preparations 'obtained'by our method'may be clarified'and con-f centrated in theiliquid' phase, and are 'immediately suitable either for storage or for usein commercial processing without further'treatment. Furthermore, by carrying out our process under certain conditions, for example i at'elevated temperatures in closed containers, itispossible 7 losses and reduce the ex-f traction periodnecessary to obtain yields to minimize solvent of extracted prolamines; s

We have found a number'oforganic'prolamine mixtures. We may use aliphatic alcohols such as methyl, ethylyand the propyl alcohols, .aliphatic k'etones such as acetone, certain organic oxides asdioxane, lower glycols'as ethylene glycol, and the'lower g col esters as methyl and ethyl cellos olve and Carbitol. Also, certain aromatieorg'anic' hydroxy comcost, suitable volatility, the low' viscosity of the 7 prolamine dispersions formed and their'low toxicity we prefer to use either ethyl or. isopropyl alcohol;

We have also found that :a wide variety of a ldehydes maybe used'in carrying out the process of our invention. It is desirable that the aldehyde used be misciblewith the other com- Itthis requirement is met any aliphatic, aromatic or het- I used, such as, for inponents of the extraction medium.

erocyclic aldehyde vmay be stance, formaldehyde, acetaldehyde, propionalextraction process, either arrangement or decomposition;

dehyde, butyraldehydes', crotonaldehyde, acrolein, chloral, benzaldehyde, furfuraldehyde;

Instead of an aldehyde We stances yielding aldehydes, in

may also use subthe course of the through molecular re For example hexamethylenetetramine, paraldehyde, glyoxal,

dioxane, tetrahydrodioxane or acetonyl acetone are suitable aldehyde yielding substances and may be used in our extraction process, provided that the extraction mixture is heated fora suflicient time at the necessary elevated temperature. However, because of their low cost and because of the particularly desirable properties which they 7 perature" we mean temperatures sinllciently' high so that the stabilizing reaction between the prolamine and the aldehyde takes place before the protein has had time to setto a gel. We have found that the use of temperatures substantially above room temperature has the further advantage of hastening the extraction. Hence to reduce the extraction cycle and minimize losses of materials by evaporation we prefer to conduct the extraction at temperature above those at which the extraction mixture would normally boil at atmospheric pressure, by carrying out the extraction process in sealed containers such as autoclaves. However, our inven-- tion isnot limited to such a method of operation. Extraction of prolamines: may also be effected according to the process of our invention, by, heating the prolamine containing material with a dispersing medium in the presence of an aldehyde, to temperatures. lower than the boiling point of the mixture and under atmospheric presure. Under. such conditions, however, ex-- traction takes place less rapidly audit is necessary to carry out the process over longer periods of time. For example we have found that extraction of zein from corn gluten by heating the gluten with a mixture of aqueous 85 percent iso- Example I A mixture of 300 parts of crude corn gluten,

760 parts or aqueous 80% ethyl alcohol and 49 parts of 37% formaldehydesolution were. placed in a sealed container and heated with agitation at 120 C. for 15 minutes, after which the mixture was cooled and filtered through diatomaceous earth. The filtrate contained 13.5 parts of zein in 100 parts of solvent, and was found to produce clear, smooth, water-resistant films when applied to paper, glass, and other surfaces. The filtrate was also found to resistgelation for many months when stored at room temperature.

A portion of the filtrate was thoroughly mixed with an equal volume of hexane to remove part of the coloringmatter from the dispersion and to concentrate the protein into a heavy liquid phase, which, when redispersed by the addition propyl alcohol containing 5 percent by volume of v acetaldehyde, to 65 C. for 15 minutes isunsatisfactory both in respect to yield of extracted zein and in resistance of the extracted zein dispersion to gelatin, and that prolonged heating is necessary to achieve satisfactory results. If however the foregoing, extraction is conduced at 120 C. by heating the mixture in an'autoclave,

. applied to paper, glass, and other surfaces.

of a small amount of strong'alcohol was found to be stable toward gelation for a long period at room temperature. Analysis of this concentrate showed it to contain 20 parts of zein in 100 parts of solvent. V

The dried gluten contained 7.56% nitrogen before extraction, and 4.53% nitrogen after extraction, 7 thus indicating that our extraction process had removed approximately 56% of the total protein from the crude gluten.

Example I! I .in a sealed container and heated with agitation at 120 C. for l5 minutes, after which the mixture was cooled and filtered through -diatomaceous earth. The filtrate contained 13.2 parts of zein in 100 parts of solvent, and was found to produce clear smooth, water-resistant films when The filtrate was also found to resist gelation for many months whenstored at room temperature.

A portion of the filtrate was thoroughly mixed.

with an equal volume of isopropyl ether to re move part0! the coloring matter from the dispersion and to concentrate the protein into a heavy liquid phase, which, when redispersed in a small amount of strong alcohol was found to be stable toward gelation for a long period at room temperature. Analysis of this concentrate showed it to contain 23 parts of zein in 100 parts satisfactory extraction both in respect'to yield of extracted zein and in resistance of the extracted material to gelation is attained after a heating period of 15 minutes.

Protein films 'produced from prolamines which have been subjected to our process are superior in smoothness, lightness of color, flexibility, and in water resistance to protein films produced of solvent.

The dried gluten contained 7.56% nitrogen before extraction, and 4.58% nitrogen after extra-c tlon, thus indicating that our extraction process had removed approximately 55% of the total protein from the crude gluten.

from prolamines obtained by simple extraction with aqueous alcohol.

As illustrative embodiments of a manner in which our invention may be carried out in practice the following examples are given, wherein all parts are by weight. Also, unless otherwise stated, the mesh sizes of the crude gluten used in these examples were as follows: 24% retained on a 20 mesh screen, 34% retained on a 32 mesh screen, 30% retained on a 48 mesh screen, 6.5% retained ona 60 mesh screen, 2.7% retained on an 80 mesh screen, 2% retained on a 100 mesh screen, and 0.8% finer than 100 mesh.

Example I ll A mixture of 300 parts of crude corn gluten, 753 parts of aqueous isopropyl alcohol and 49 parts of 40% formaldehyde were placed in a sealed container and heated with agitation at 120 C. for 15 minutes, after which the mixture was cooled and filtered through diatomaceous earth. The filtrate contained 12.5 parts of zein in parts of solvent, and wasfound to produce clear, smooth, water-resistant films when applied to paper, glass, and other surfaces. The filtrate was also found to resist gelation for many months when stored at room temperature.

. A portion of the filtrate was thoroughly mixed with an equal volume of hexane to remove part of the coloring matter from the dispersion and to concentrate the protein into a heavy liquid phase,

aasaaas whichiwhen redisperseda by the"addition rotv a solvent.

'The.;dried. gluten comment-.56 1, nitrogenzbesmall iamountof strong alcohol-was foun'dto be: stable toward gelation for alongperiod: at roomtemperature. Analysis of'thi'sponcentrate;showed it tov contain."23.'3'; partsof zeinaini00 partsof fore extraction, and? 5.66%nitrogen .aiftenextra-c.

tion, thus indicating. the-tour extrac'tionvprocess V had removedapproximaitely739% -of=the;;total..j

protein-from thebrudegluten. v

Example; IV

A mixture: c1300 parts oi crude corngluten, 807 parts of aqueous 55% isopropyl. alcohol and 49 parts of 37%. formaldehyde. solution was filtrate-contained.6 parts: ot zeinin.1'00 parts 1 placed. in a sealed container and heated with agitation at.1'20 C. for 15 minutes, after'which the mixture-was cooled and filtered through diatomaceous' earth. The filtrate contained-l3.2

parts of zein in 100 partsof solvent, and. was

i'ound' to produce clear smooth, water-resistant films when applied. to paper, glass, and. other Example V A mixture of 3001 arts of crude corn gluten, 753 parts of aqueous 80% isopropyl alcohol and 49 parts of 37%'- formaldehyde solution; was

placed in a sealed container and heated. with agitation at 120 C. for 30 minutes, after-which the mixture was cooled and filtered through diatomaceous earth. The filtrate contained 135 parts of zein in 100 parts of, solvent, and was found to produce clear smooth, water resistant films when applied .to paper,.glass-, and other surfaces. The filtrate was also found to resist gelation for many months when stored at "room temperature. A portion of the filtrate was thoroughly mixed with an equal volume of hexane to remove part of the coloring matter from the dispersion and to concentrate the protein into. a heavy=1iquid .phase, which, when redispersedi by the addition of a small amount of strong alcohol, wasfound to be stable toward gelation for a long period at room temperature. Analysis of this concentrate showed it to contain. 27.8- parts of zein in 1,00

parts of solvent.

The dried gluten contained 7.56% nitrogen before extraction, and. 5.20% nitrogen after extraction, thus indicating that our extraction process had removed approximately 46% of the total protein from the crude gluten.

Example V-I A mixture of 300 parts-oi crudecorn gluten.

753 parts of aqueous 80% isopropyl alcohol and 27 parts of acetaldehyde were placed in a sealed container and heated with agitation at, 120 C.

for 15 minutes, after which the mixture was.

cooled and filtered through diatomaceous earth.

paper, glass, and other surfaces.

The dried gluten contained 7.56% nitrogen betemperature.

l Example; m;

A mixtureof '300- parts o't-iii'nly ground crude tainer andheated with agitationat 120 C.Wfo'i' 15 minutesfaiter which the mixture-was cooled 7 and. filteredthrough diatomaceous ear-m. The

of solvent, andv was found .to produce clear,

smooth, wa-ter-resistant films when applied to paper; glass, and other suriaces. The filtrate was also foundto resist gelation for many monthswhenstored at room temperature.

A portion of the filtrate was thoroughly mixed with an equal vol-umeof hexane-.to-remove part of.

the coloring, matter from the dispersion and to concentrate theprotein into aheavy liquid phase,

which, when redispersed by the addition of a small: amount of strong' alcohol, was found to be stable toward. gelation for a long period at room "temperature. Analysisof this concentrate showed it to contain 26.8 parts. ofv zein in 100. parts of solvent.

The dried gluten contained 7.84%.: nitrogen before extraction, and"5.04% nitrogen afterextraction, thus indicating that our extraction process had removed approximately 521% of theftotsl protein from the crude gluten.

Example VIII A' mixture of 300 parts of crude corn gluten, 836 parts of aqueous 80% isopropyl alcohol and 50 partsof butyraldehyde "were placed in a sealed container and heated with agitation at 120 C.

for 15. mi'nu.tes, after which the mixture 'was cooled and filtered through. diatomaceous earth on a plate press. The filtrate contained 11.7

parts of zein in 100 parts of solvent, and was found to produce clear, smooth, water-resistant films when applied to paper, glass, and other surfaces. The filtrate was also found to resist gelation for many months when stored at room A portion of the filtrate wasv thoroughly mixed with an equal volume of hexane to remove part of the coloring matter from the" dispersion and to concentrate the protein into aheavy liquid phase, which, when redispersed by the addition of a small amount of. strong alcohol, was. found to be stable toward gelation for: along period at room temperature. Analysis of this concentrate showed? it to contain 23:2parts-oftzein in 100 parts: of solvent.

The dried gluten contained 7.56% nitrogen before extraction, and 5.45%Initrogen after extraction, thus indicating thato'ur extraction process had removed approximately 42% of the total protein from the crude gluten. j

In. the foregoing examples the process of our invention is illustrated as applied to the extrac- .tion-of zein from corn gluten. As previously I fore extraction; and "4.913%. nitrogen after 'ex traction, thus indicating?that.::our .extractionr processrhad: removed approximately 50% of the total protein from the crude gluten; a

corn gluten, aqueous isopropyl alcohol, and formaldehyde and heating 'said: mixture ina sealed contained to a temperature 'of' about 1120". C.

2. The process-of extracting mm 3 from corn gluten which comprises forming a mixture 01- corn gluten, aqueous isopropyl alcohol and acetaldehyde and heating said mixture in a sealed container to aternperature of about 120 C a v 3. The process of extracting prolamines in a form that will resist gelation on prolonged stand-I ing comprisingmixing together grain gluten, a

prolamine dispersing agent, and an aldehyde, v agitating and heating the mixture at a tempera-- ture of about 120 C. for about 15 to 30 minutes,

whereby the reaction betweentheprolamine and the aldehyde is stabilized before the protein has -time to gel, thence filtering the reaction mixture and recovering the prolamine containing filtrate.

4. Theprocess' of extracting prolamines in a theprolamine and the aldehyde is stabilimdbefore the protein has time-t0 gel, thence filtering the reaction mixture andrecovering the filtrate 

